Copying apparatus having a magnification changing function

Abstract

A copying apparatus capable of varying the imaging magnification of the image of an original projected upon a photosensitive medium has an imaging optical system for forming the image of the orignal on the photosensitive medium, and a member for supporting the imaging optical system. The imaging optical system is provided with a plurality of optical elements. At least one magnification changing optical element of the optical elements is capable of changing its position relative to the other optical elements to vary the focal length of the imaging optical system. The member for supporting the imaging optical system includes a first device capable of moving at least one of the magnification changing optical elements by a minute amount in the direction of the optical axis, and a second device for moving the magnification changing optical elements by a predetermined amount to vary the focal length of the imaging optical system.

What I claim is: 
     
       1. In a copying apparatus capable of varying the imaging magnification of the image of an original projected upon a photosensitive medium, a combination comprising: an imaging optical system for forming the image of the original on the photosensitive medium, said imaging optical system comprising a plurality of optical elements, including at least one magnification changing optical element capable of changing its position relative to the other said optical elements to vary the focal length of said imaging optical system; and   a member for supporting said imaging optical system, said member including first moving means for moving said one magnification changing optical element by a minute amount in the direction of the optical axis to compensate for variations in tolerance in the copying apparatus, and second moving means for moving said magnification changing optical elements by a predetermined amount to vary the focal length of said imaging optical system said second moving means moving said magnification changing optical elements independently of said first moving means.   
     
     
       2. A copying apparatus according to claim 1, further comprising means for moving said imaging optical system as a unit during magnification change. 
     
     
       3. A copying apparatus according to claim 2, wherein said imaging optical system is an optical system capable of effecting continuous magnification change. 
     
     
       4. In a copying apparatus capable of varying the imaging magnification of the image of an original projected upon a photosensitive medium, a combination comprising: a zoom lens system for projecting the image of the original onto the photosensitive medium, said zoom lens system including a magnification changing lens element;   an inner barrel supporting said magnification changing lens element of said imaging lens system;   an outer barrel provided in contact with said inner barrel;   a first moving means for moving only said inner barrel in the direction of the optical axis of said zoom lens system; and   a second moving means for moving said inner barrel along a predetermined zooming locus.   
     
     
       5. A copying apparatus according to claim 4, wherein said zoom lens is of a symmetrical shape relative to a diaphragm. 
     
     
       6. A method of adjusting the optical system of a copying apparatus capable of varying the imaging magnification of the image of an original projected upon a photosensitive medium, comprising the steps of: moving at least one lens element movable for magnification change in an imaging optical system, by means of a moving mechanism distinct from that for magnification change, to cause two points disposed at predetermined positions to assume an optically conjugate positional relation; and   moving a reflecting member disposed between the surface of the original and the photosensitive medium to render the surface of the original and the photosensitive medium to assume optically conjugate positions by disposing said imaging optical system in said copying apparatus.   
     
     
       7. In a copying apparatus capable of varying the imaging magnification of the image of an original projected upon a photosensitive medium, a combination comprising: an imaging optical system for forming the image of the original on the photosensitive medium, said imaging optical system comprising a plurality of optical elements, including at least one magnification changing element capable of moving from a starting point along a predetermined path to change the position of said one optical element relative to the other said optical elements to vary the focal length of said imaging optical system; and   a member for supporting said imaging optical system, said member including first moving means for adjusting the position of said starting point relative to at least one of the others of said optical elements while maintaining the distance between said starting point and one end of said predetermined path constant to compensate for variations in tolerance in the copying apparatus, and second moving means for moving said one optical element to vary the focal length of said imaging optical system.